Submerged core heat exchanger

ABSTRACT

A heat exchanger having all of the separate cores thereof mounted together to form a single core assembly which is removably mounted within a cylindrical pressure vessel. The vessel is supplied with a refrigerant of sufficient depth to either partially or entirely cover the assembly. The separate cores have their respective inputs and outputs manifolded to separate pipes which pass through the walls of the vessel and permit circulation of the fluid to be cooled through the cores.

United States Patent Joseph P. Rutledge Brussels, Belgium Apr. 21, 1969 Feb. 16, 1971 Stewart-Warner Corporation Chicago, 111.

a corporation of Virginia Inventor Appl. No. Filed Patented Assignee SUBMERGED CORE HEAT EXCHANGER 2 Claims, 4 Drawing Figs.

11.8. C1. 165/74, 165/78, 62/389 Int. Cl. F28d l/06 Field ol'Search 165/78, 74; 62/389 [56] References Cited UNITED STATES PATENTS 1,255,502 2/1918 Benjamin 165/74 1,299,955 4/1919 Jones 165/78 1,302,625 5/1919 Benjamin 165/78 2,615,687 10/1952 Simmons 165/78 Primary Examiner-Meyer Perlin Attorneys-Augustus G. Douvas, William .1. Newman and Norton Lesser ABSTRACT: A heat exchanger having all of the separate cores thereof mounted together to form a single core assembly which is removably mounted within :a cylindrical pressure vessel. The vessel is supplied with a refrigerant of sufficient depth to either partially or entirely cover the assembly. The separate cores have their respective inputs and outputs manifolded to separate pipes which pass through the walls of the vessel and permit circulation ofthe fluid to be cooled through the cores.

PATENTEU FEBJ s IBYI I Cg zoEn:

INVENTOR -JOSEPH P RUTLEDGE ATTORNEYS.

l SUBMERGED COREHEATEXCHANGER BACKGROUND OF THEINVENTION l. Field of the Invention I This invention'relates to heat exchangers and more particularly to a heatexchanger having a unitized core assembly which is submerged in a refrigerant contained in a single vessel.

2. Description of the Prior Art Heat exchangers of the refrigerant type, normally employ separate vessels, each consisting of a core having domed end closures on the top and bottom of each core. The domed end closures of each separate vessel are manifolded into pipes, located above and below the vessel. The pipe located below the vessel introduces the refrigerant in liquid form to the vessel and the pipe located above the vessel provides for the exhaust of the refrigerant vapor. i

The input and exhaust pipes of each core are similarly manifolded into common pipes located on either side of the vessel.

The cost of such heat exchangersis very high due to the fact that each core must have two d o'med end closures sealed thereto and each end closure must be separately manifolded to the refrigerant supply and exhaust pipes.

In addition to the high cost of fabricating such prior art heat exchangers, their use often requires the presence of expensive supplemental equipment in any system employing them. This supplemental equipment usually takes the form of a liquid vapor separation drum in the suction line between the heat exchanger and the compressor. The purpose of this separation drum is to insure that the vapor reaching the compressor is dry and free from any liquid which may be present in it as a result of the boiling action of the refrigerant.

SUMMARY OF THE INVENTION This invention is directed to'heat exchangers wherein all of the cores of the exchanger are connected to form a single unitized assembly. This unitized assembly of the cores is then mounted in a single sealed vessel into which a refrigerant such as propane is introduced. Separate pipes pass through the end or sidewalls of the vessel and each isconnected to the input and output of the cores respectively. This connection of pipes permits the circulation of the fluid to be cooled through the cores.

The refrigerant introduced is in liquid form and is of sufficient depth to partially submerge the assembly of cores. This results in the vessel being filled toapproximately one-half to two-thirds of its capacity with the liquid refrigerant. The remaining portion of the vessel provides space for the vapor produced as a result of the boiling refrigerant. This vapor is then exhausted from the remaining portion of the vessel through piping located at the top of the vessel. By submerging the entire core assembly in a common'refrigerant, the added expense of providing separatef;vessels for each core is eliminated as is the extensive. piping required to supply refrigerant to each separate vessel; l naddition to the substantial cost savings, the unique design'of the present invention permits the elimination of the additional liquid-vapor separation stages required by prior art :heat exchangers. These separation stages take the form of liquid vapor separation tanks which are connected between the source of vapor to be dried and the suction side of a compressor. The liquid separation tank functions to reduce the.velocity.of the vapor flow from the source thus permitting any liquid present to settle out of the vapor before it reaches the compressor.

The large volume of space present between the top of the liquid refrigerant and the wall of the vessel of the present invention performs the same function as the liquid separation tank required in prior art heat exchangers. The velocity of the vapor resulting from the boiling of the liquid refrigerant is reduced considerably in the space above the refrigerant thus permitting any liquid present in the vapor to separate out and return to the refrigerant before it can be sucked into the compressor.

BRIEF DESCRlPTlONOF THE DRAWING FIG. 1 is a side view ofa heat exchanger as exemplified by the prior art.

FIG. 2 is a sectional end view taken about lines 2-2. t.

FIG. 3 is a sectional elevation view of the heat exchanger of the present invention.

HO. 4 is a sectional end view of-heat exchanger of FIG. 3 taken about lines 44.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, a heat exchanger 10 is shown as being of cylindrical shape having a center portion consisting of a hollow cylindrical shell 12 of steel or other suitable material. An elliptical-shaped head 14 encloses one end of the cylindrical shell and is secured to the end by any suitable means. such as welding. The other end of the cylindrical shell 12 is enclosed by a second elliptical-shaped head 16 which is removable. Secured to the outer periphery 18 of head 16 is a circular flange 20 which mates with a similar shaped flange 22 secured to the outer periphery 24 of the shell! 12. A gasket 26 of, for example, silicone rubber is placed between the flanges 20, 22 to provide a tight seal when the flanges are drawn together by bolts (not shown). A circular aperture 28 is located in the bottom-center portion of the shell 12. A plate 30 surrounds the aperture 28 and provides reinforcement for the edge of the aperture. A pipe 32 is welded to the shell 12 and the reinforcing plate 30. The pipe has a blind flange 34 welded to it for connection to a source of refrigerant such as methane, ethylene, or propane. A similar circular aperture is located on the top center portion of the shell 12 and has a reinforcing plate 36 surrounding it. A pipe having a blind flange 40 is welded to the shell 12 and reinforcing plate 36. A slip flange 42 is provided for connection to an'external source of suction. Gasket 44 located between the flanges 40, 42 insures a tight seal.

The shell 12 is supported by four legs 46 which are secured to longitudinal members 48. The upper portion of the legs 46 have curved portions 50 and pads 52 which form a cradle for supporting the shell 12. Guide tracks 54, 54' are positioned opposite each other and secured to the inside wall of shell 12. Guide tracks The guide tracks 54,54 extend the length of shell 12 and support the core assembly and the associated piping ofthe heat exchanger as will now be described.

In the preferred embodiment, the core assembly of the heat exchanger consists of numerous cores 56 which are arranged in pairs extending the length of the shell 12. The cores 56 are preferably of the plate fin exchanger type which lend them selves to multiple fluid operation. Each pair of cores 56 is mounted in side-by-side relationship by means of plate 58 secured to the sides of the cores, perpendicular to the guide track 54,54. On the bottom ofeach plate 58 is mounted a pair of guide shoes 60, 60' spaced apart to fit in sliding engagement with guide track 54,54 located on the inside wall of shell 12. ln order to facilitate sliding of guide shoes 60.60 on guide track'54,54, nylon pads 62, 64 are. riveted to the surfaces of guide shoes 60,60 facing the guide track.

Each core 56 has a pipe 66 extending from the top portion thereof which is manifolded into a larger pipe 68 running above the core pairs. The pipe 68 is positioned equidistant from each core of the pair, and supplies the fluid to be cooled to the various cores 56. One end of pipe 68 extends through removable head 18 and is welded thereto to provide a seal; the

of heat exchanger of FIG. 1

' other end of the pipe 68 is sealed by means of cap 70.

Each core 56 has a second pipe 72 extending from the bottom of the core and manifolded into a larger pipe 74 also positioned equidistant from each core of the pair. The pipe 74 exhausts the cooled fluid from the various cores 56. One end of pipe 74 extends through removable head 18 and is sealed thereto by welding; the other end is sealed by means of a cap 76. Reinforcing plates 78, 78 are positioned around pipes 68, 74 and in contact with the outer surface of the removable head 18. Pipes 68, 74 have on their open ends, blind flanges 80, 82 respectively, for mating engagement with slip-on flanges 84, 86 respectively. The slip-on flanges 84, 86 are then welded to pipes which supply and exhaust the fluid to be cooled. Upon fabrication of the cores 56 into pairs and their connection to pipes 68, 74, the entire core assembly can be slid into shell 12 on shoes 60,60 and guide tracks 54, 54'. The removable head 18 is positioned on and secured to pipes 68, 74 such that when the core assembly is entirely within the shell 12, the flange 20 on the removable head 18 is in engagement with flange 22 on the shell 12. It should be noted that the cores 56 can also be arranged in series relationship to each other rather than in parallel relationship as disclosed in the preferred embodiment. lf several different fluids are to be cooled in each core 56, additional piping similar to that previ 'ously discussed would be used.

Numerous bolts (not shown)'located between the flanges 20, 22 are then tightened to draw the flanges together to seal the core assembly in the shell 12. The quantity of cores 56 which comprise the core assembly can vary from one to several depending on the desired capacity of the heat exchanger.

In operation, the liquid refrigerant is introduced to the vessel through the pipe 30 located in the bottom of the vessel. The liquid refrigerant then rises in the vessel covering the lower manifold pipe 74. As the liquid refrigerant continues to rise, it surrounds each individual core- 56, thus providing each core with an equal cooling effect. The fluid to be cooled is then pumped into the upper manifold 68 and from there into each core 56 by way of pipes 66. The liquid refrigerant surrounding each core 56 boils due to the lack of sufficient vapor pressure in the area of the vessel between the top of the refrigerant and the upper walls of the vessel 12. As the refrigerant boils, heat is absorbed from the fluid in the cores 56, thus cooling it. The cooled fluid is then pumped out of the cores 56 through the bottoms thereof by way of pipes 72 which lead into the lower manifold pipe 74. As the refrigerant vaporizes due to its boiling, the vapor enters the large space above the refrigerant and the walls ofthe vessel 12. Due to this large space, the velocity of the vapor passing through it to exhaust pipe 38 is relatively slow. This low vapor velocity permits any small particles of liquid refrigerant still in the vapor to settle out of the vapor and backto the surface of the liquid refrigerant before they can be exhausted through pipe 38. As the liquid refrigerant vaporizes, more refrigerant is supplied to the vessel through pipe 32 at the bottom of the vessel in order to keep the cores 56 submerged. 1

While the invention. has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and the details may be made therein without departing from the spirit and scope ofthe invention.

lclaim:

1. In the heat exchanger for use with a liquid refrigerant comprising:

a. a cylindrical-shaped vessel having a longitudinal axis generally parallel to the ground plane upon which said vessel is to be supported, a plurality of plate fin heat exchanger cores in said vessel for submersion in said liquid refrigerant, each core being spaced from the inner wall of said vessel and from each other adjacent to and along the longitudinal axis of said vessel to provide maximum circulation of said liquid refrigerant around and in contact with said heat exchanger cores;

b. means on said vessel located intermediate said longitudinal axis and said ground plane for allowing the introduction of said refrigerant to a level in said vessel coincident with said cores in said vessel whereby the evaporating surface of said liquid extends parallel to said axis for providing a relatively large area of evaporation and a correspondingly large volume above said refrigerant for enabling separation of refrigerant liquid from the vapor in said volume; I c. further means on said vessel spaced above said longitudinal axis for removing from said vessel the vapor formed by the boiling of said liquid refrigerant whereby the vapor generated at said surface parallel to said longitudinal axis is transmitted from said vessel;

d. closed end walls for said vessel with one of said end walls being removable from said vessel; and

e. means including a pair of pipes extending through said one removable wall for circulating the fluid to be cooled through said cores whereby a heat transfer is effected between said fluid to be cooled and said refrigerant.

2. In the heat exchanger claimed in claim 1 stationary guide tracks in said vessel extending parallel to said longitudinal axis, and guide shoes fixed to said cores for sliding engagement with said stationary guide tracks whereby said cores may he slid into said vessel on said stationary tracks. 

1. In the heat exchanger for use with a liquid refrigerant comprising: a. a cylindrical-shaped vessel having a longitudinal axis generally parallel to the ground plane upon which said vessel is to be supported, a plurality of plate fin heat exchanger cores in said vessel for submersion in said liquid refrigerant, each core being spaced from the inner wall of said vessel and from each other adjacent to and along the longitudinal axis of said vessel to provide maximum circulation of said liquid refrigerant around and in contact with said heat exchanger cores; b. means on said vessel located intermediate said longitudinal axis and said ground plane for allowing the introduction of said refrigerant to a level in said vessel coincident with said cores in said vessel whereby the evaporating surface of said liquid extends parallel to said axis for providing a relatively large area of evaporation and a correspondingly large volume above said refrigerant for enabling separation of refrigerant liquid from the vapor in said volume; c. further means on said vessel spaced above said longitudinal axis for removing from said vessel the vapor formed by the boiling of said liquid refrigerant whereby the vapor generated at said surface parallel to said longitudinal axis is transmitted from said vessel; d. closed end walls for said vessel with one of said end walls being removable from said vessel; and e. means including a pair of pipes extending through said one removable wall for circulating the fluid to be cooled through said cores whereby a heat transfer is effected between said fluid to be cooled and said refrigerant.
 2. In the heat exchanger claimed in claim 1 stationary guide tracks in said vessel extending parallel to said longitudinal axis, and guide shoes fixed to said cores for sliding engagement with said stationary guide tracks whereby said cores may be slid into said vessel on said stationary tracks. 